Writing head for a tube writing pen



1 9, 1969 H. RIEPE 3,466,132

WRITING HEAD FOR A TUBE WRITING PEN Filed March 13, 1967 2 Sheets-Sheet 1 l g 52 4 E k 6 Q; M i \5 E INVENTOR.

HELMUTH RIEPE ATTDRNEY WRITING HEAD FOR A TUBE WRITING PEN Filed March 15, 1967 2. Sheets-Sheet 2 INVENTOR. HEL MUTH RIEPE ATTORNEY United States Patent 3,466,132 WRITING HEAD FOR A TUBE WRITING PEN Helmuth Riepe, Hamburg, Germany, assignor, by mesne assignments, to Rapidograph, Inc., Bloomsbury, N.J., a corporation of New Jersey Filed Mar. 13, 1967, Ser. No. 622,678

A. a Claims priority, application Germany, Mar. 12, 1966,

Int. (:1. B43k 1/10 4 Claims ABSTRACT OF THE DISCLOSURE Disclosed herein is a writing head for a tube writing pen, wherein a cylindrical body of the writing head is formed with a bore for the reception of a drop weight adjoining a mount for a writing tube in which a hair wire aflixed to the bottom end of the drop weight is movable, and wherein the inwardly extended end of the cylindrical body is formed with a low pitched screw thread which serves as a pressure balancing chamber and which communicates with a bore leading to the outside, the inwardly extended end being so contrived that a shank of smaller diameter than that of the cylindrical body rearwardly adjoins the end of the cylindrical body and forms an aunular shoulder, and that the threads which function as the pressure balancing chamber are cut into this rearwardly extending shank.

Background of the invention So-called tube writing pens comprising a barrel with a writing head inserted or screwed into one end of the same have become increasingly popular as useful drawing utensils. The writing heads of such tube writing pens may consist of a cylindrical body containing a drop weight inside a bore and a tube mount in the blunt tapering end of the cylindrical body. Attached to the drop weight which is movable inside the cylindrical body is a hair wire which extends through the writing tube. The object of the drop weight and hair Wire is to control the feed of the India ink and to prevent blockage of the bore of the writing tube.

A previously proposed arrangement consists in providing these tube writing heads with a helical venting channel which communicates with the main ink reservoir through a radial bore in the upper part of the cylindrical mount. This venting channel has the purpose of permitting the pressures to equalize and of receiving the expanding India ink. When the ink is heated or a pressure differential develops, the venting channel prevents the ink from dribbling out of the end of the writing tube. Hitherto, it has been the practice to cut this helical venting channel into the upper part of the cylindrical body of the tube writing head, and it was relatively steeply pitched. Moreover, the helical venting channel has in the past been cut into the same peripheral surface that also carries the tightly pitched screw threads which are provided for screwing the writing head into the barrel of the tube writing pen. The rear opening of the writing head communicates either with the main ink reservoir inside the barrel of the pen, or it may be pushed over ink chambers in the form of cylindrical plastics tubes or cartridges with a closed bottom end.

All these arrangements have two major drawbacks. On the one hand, two intersecting threads of different pitch, namely the venting channel and the screw thread, must be cut into the writing head, a necessity which considerably. complicates production and, on the other hand, the relatively short venting channel communicates with the outside air, causing the ink to dry and to block the venting Patented Sept. 9, 1969 channel. This results in irregularities in the feed of the ink or the head must be frequently unscrewed and the threads cleaned, a necessity which is a nuisance.

Summary of the invention It has now been recognized that it is better, instead of a venting channel, to provide a pressure balancing chamber which, though also communicating with the outside atmosphere, is nevertheless, sufficiently long for the pressure drop of the water vapor partial pressure to be distributed along a path of adequate length to prevent the ink from becoming dry. If this pressure balancing chamber is provided on the inner, that is rear part of the cylindrical body, then it may have the form of a helix of shallow pitch and sufficient length. On the one hand, this does away with the two intersecting threads and, on the other hand, cleaning of the pressure balancing chamber is greatly simplified because the inwardly extended end of the cylindrical body and the exposed pressure balancing chamber need merely be cleaned and deposits wiped off with a piece of blotting paper when the pen. is being refilled.

The present invention, therefore, provides a writing head for a tube writing pen, wherein a. cylindrical body of the writing head is formed with a bore for the reception of a drop weight adjoining a mount for a writing tube in which a hair wire affixed to the bottom end of the drop weight is movable, and wherein the inwardly extended end of the cylindrical body is formed with a low pitched screw thread which serves as a pressure balancing chamber and which communicates with a bore leading to the outside.

Preferably, the inwardly extended end is so contrived than a shank of smaller diameter than that of the cylindrical body rearwardly adjoins the end of the cylindrical body and forms an annular shoulder, and that the threads which function as the pressure balancing chamber are cut into this rearwardly extending shank.

Brief description of the drawings In order to enable the invention to be more readily understood, reference will now be made to the accompanying drawings, which illustrate diagrammatically and by way of example, two embodiments thereof, and in which:

FIGURE 1 is a side view, partly in longitudinal section, of a writing head of conventional kind.

FIGURE 2 is a longitudinal section of one embodiment of a writing head according to the invention, comprising a radial outlet channel for the pressure balancing chamber.

FIGURE 3 is a view similar to FIGURE 2, of another embodiment with an axial outlet channel.

The hitherto conventional writing head of a tube writing pen comprises a cylindrical body 2 with a central bore 6 (see FIGS. 2 and 3) containing a drop weight 4 and, adjoining this cylindrical body 2, a tube mount 8 from which a hair wire 10 (see FIGS. 2 and 3) attached to the drop weight protrudes. The upper end of the cylindrical body 2 has a suitably threaded surface 12, for screwing the tube writing head into a barrel. Normally these threads are closely pitched. This threaded region also contains a helical venting channel 14 which terminates at the upper edge.

The upper end of the cylindrical body 2 may also be fitted with a metal hoop 18 which prevents the drop weight 4 from falling out of the upper end of the body but nevertheless permits manual cleaning to be effected without the necessity for removing the weight. This metal hoop 18 is U-shaped and, whenever this should fall towards the hoop the latter intercepts the face 20 of the weight. The bottom ends 26 of the two lateral arms 24 of the hoop 18 are bent outwards and engage radial openings 28 of which at least one, as shown in FIG. 1, is located in the region of 3 the venting channel 14. At body 2 is formed with a collar 32 with at least two flats for the application of a tool. Below the collar the cylindrical body tapers towards the tube mount.

Description of the preferred embodiment its bottom end, the cylindrical,

ing portion of the tube mount which is embraced by the I sealing cap when this is pushed onto the head.

In the first arrangement according to the present invention, which is shown in FIG. 2, the inwardly extended end 40 of the cylindrical body 2 is formed with threads 42 which serve as a pressure balancin chamber, and which terminate in a recess 44 extending radially outwards in an annular shoulder. This shoulder is formed as the result of the diiference in diameter between the cylindrical body 2 and its rearward end or shank 40. The pressure balancing chamber 42 communicates with the ink chamber 6 via the channel 44. The pressure balancing chamber 42 also communicates with the outside atmosphere through a small bore 49 and an annular space 45.

In the embodiment illustrated in FIG. 3, the extended end 40' likewise carries a pressure balancing chamber 42 in the form of a helical groove of shallow pitch. However, this helical groove communicates with a bore 46 extending parallel to the axis of the utensil and ending in the bluntly tapering part 8 of the tube mount. The pressure balancing chamber 42 communicates with the ink chamber 6 via the channel 44. Preferably, a cap 48 for the utensil contains a sealing insertion 50 which reduces the air space available in the cap to a minimum. It also helps to prevent the ink from drying out. This sealing insertion 50 has a lip 52 which makes sealing contact with the front end of the cylindrical body, and it thus satisfactorily seals off the air space 56. It is essential that the end 57 of the axial bore 46 should be within this sealed air space between the tube mount and the sealing insertion 50.

Although the present invention has been described in some detail by way of illustration, it is understood that certain changes andmodifications may be made within the spirit of the invention and scope of the appended claims.

What is claimed is: v

1. A writing pen comprising a barrel and a writing head adapted to be inserted into said barrel, said writing head having a cylindrical body and being provided with a bore for the reception of a drop weight adjoining a mount for a writing tube in which a hair wire affixed to the bottom end of the drop weight is moveable, said barrel having internal threads, said cylindrical body having external threads for threadedly engaging the threads within said barrel, the inwardly extending end of said cylindrical body being formed with a low pitched helical groove defining an elongated pressure balancing chamber which communicates with a bore leading to the outside, and said low pitched helical groove being separate and spaced apart from said threads formed on said cylindrical body.

'2. A writing pen as claimed in claim 1, wherein the end of the cylindrical body has a rearwardly extending shank of smaller diameter than that of the cylindrical body, thus to form an annular shoulder, the helical groove which functions as the pressure balancing chamber being formed in the rearwardly extending shank. I

3. A writing pen, as claimed in claim 2, wherein the bore leading to the outside from the pressure balancing chamber is formed in the annular shoulder in the form of a recess extending radially outwards.

4. A writing pen as claimed in claim 2, wherein the bore leading to the outside from the pressure balancing chamber is a bore extending parallel to the axis of the writing head formed in the wall of the cylindrical body issuing in the blunt tapering portion of the tube mount in the region which is embraced by a sealing cap when this is mounted on the head.

References Cited UNITED STATES PATENTS 698,859 4/1902 Sanford 401259 1,425,150 8/1922 Ullrich 401-259 2,713,848 7/1955 Miessner 401-243 X LAWRENCE CHARLES, Primary Examiner 

